As a general library device, there is an instance having a configuration disclosed in patent document 1 (Japanese Patent Application Laid-Open No. 2008-217938), for example.
As shown in FIG. 7, a library device 1 of patent document 1 is configured including: a medium storing means (cartridge magazine 5) having a cell 4 which individually stores a plurality of media (data cartridge 2) storing various kinds of information; a medium reading and writing means (drive device 3) that loads the data cartridge 2, to read and write information; and a medium transfer means (accessor mechanism 6) for accessing a predetermined cell 4, to put in or take out the data cartridge 2, or putting in or taking out a data cartridge into/from the predetermined drive device 3, and the like.
Furthermore, there is an instance, which controls a move of the accessor mechanism 6, as shown in FIG. 7 (a move in X-direction or Y-direction shown in FIG. 7) using a stepping motor.
When the move of the accessor mechanism 6 as shown in FIG. 7 (in X-direction shown in FIG. 7, for example) is controlled using the stepping motor, the accessor mechanism 6 will move by a distance according to a number of pulses of the stepping motor (a movement distance of the accessor mechanism 6=the number of pulses of the stepping motor*a movement distance that the accessor mechanism 6 can move by one pulse). For this reason, as shown in FIG. 8, when the accessor mechanism 6 is desired to be moved to a specific designated position (the position of B in FIG. 8) from the home position (the position of A in FIG. 8), for example, it is possible to move the accessor mechanism 6 from the home position A to the designated position B by driving the stepping motor by the number of pulses according to the movement distance from the home position A to the designated position B. FIG. 8 shows an example of moving the accessor mechanism 6 shown in FIG. 7 in X-direction using the stepping motor.
However, when a step-out or the like occurs to the stepping motor, although the accessor mechanism 6 does not move, only the number of pulses of the stepping motor is counted. For this reason, when the step-out or the like occurs to the stepping motor, the number of pulses of the stepping motor and the movement distance of the accessor mechanism 6 do not synchronize, and thus, even if the stepping motor are driven by the number of pulses according to the movement distance from the home position A to the designated position B, the accessor mechanism 6 could not be moved from the home position A to the designated position B.
For this reason, there is an instance, in which the accessor mechanism 6 is moved using the stepping motor and the movement distance of the accessor mechanism 6 can be verified with an encoder count number counted by an encoder sensor. In this case, the number of pulses of the stepping motor and the encoder count number counted by the encoder sensor will be made to have a correlation. Specifically, it is made such that the encoder count number counted by the encoder sensor when the stepping motor is driven by the predetermined number of pulses (an actual encoder count number) will be an assumed encoder count number obtained by multiplying the predetermined number of pulses by a proof factor (the predetermined number of pulses*the proof factor). That is, it is made such that the assumed encoder count number (the predetermined number of pulses*the proof factor)=the actual encoder count number.
In this case, when the accessor mechanism 6 is desired to be moved from the home position A to the designated position B, the stepping motor is driven by the number of pulses according to the movement distance from the home position A to the designated position B, and, at the same time, the encoder count number which has been counted by the encoder sensor until the stepping motor is driven by that number of pulses is checked. Then, it is confirmed whether or not there is a correlation between the number of pulses of the stepping motor and the encoder count number (whether they satisfy a relation that the number of pulses of the stepping motor*proof factor=actual encoder count number), and, when there is a correlation between the number of pulses of the stepping motor and the encoder count number (when they satisfy the relation that the number of pulses of a stepping motor*proof factor=actual encoder count number), it is determined that the accessor mechanism 6 has moved to the designated position B. When there is no correlation between the number of pulses of the stepping motor and an encoder count number (when they do not satisfy the relation that the number of pulses of the stepping motor*proof factor=actual encoder count number), it is determined that the accessor mechanism 6 has not moved to the designated position B. As a result, it is possible to move the accessor mechanism 6 using the stepping motor, and check the movement distance of the accessor mechanism 6 by the encoder count number counted by the encoder sensor.
However, there is a case where, by any extrinsic factors, the relation between the number of pulses of the stepping motor and the encoder count number (the relation that the number of pulses of the stepping motor*proof factor=actual encoder count number) is changed, and, as a result, it becomes impossible to check the movement distance of the accessor mechanism 6 any more by the encoder count number counted by the encoder sensor. As the extrinsic factor, a case where the module of gears, of which the accessor mechanism 6 is composed, has been changed or the like is mentioned.
For this reason, development for a mechanism, which can confirm the movement distance of the accessor mechanism 6 by the encoder count number counted by the encoder sensor even if the relation between the number of pulses of the stepping motor and the encoder count number (the relation that the number of pulses of a stepping motor*proof factor=actual encoder count number) is changed, is needed.
Meanwhile, as a technical document filed prior to the present invention, there is a literature which discloses a technology which can perform, when there is a change in a structure of a library device, processing to update location information on all frames easily in a short time by limiting such cases (for example, refer to patent document 2).
In the above-mentioned patent document 2, in a case where an accessor or an accessor component of a library device is replaced, by the accessor before the replacement, position control information for a standard unit is measured in advance and is made to be first position control information, and, in addition, position control information for each frame is measured in advance and is made to be second position control information. Next, position control information for the standard unit is measured by the accessor after the replacement and is made be third position control information. Then, a difference value between the first position control information and the third position control information is obtained, then the second position control information is corrected by the difference value and is made to be fourth position control information. Then, the operation of the accessor after the replacement will be controlled based on the fourth position control information.